New from Michelin, Airless Tires Labeled the 'Tweel'.

The all new airless tire from Michelin recently came out into the publics eye early this year, 2005. Although it appears to be a pretty good idea and concept, they probably will not be available to the general public soon. I have looked at the idea and think it is cool, although I don't know what to think of the center rim selection that you haven't got a choice with. I'm sure that the police will probably not like the idea because the spike strips will definitely be ineffective with a set of these on your ride. The ride and handling seem to be very effective.

Now, after decades spent persuading the world to ride on air, the company has begun work on an innovation that could render the pneumatic tire obsolete. Engineers at Michelin's American technology center are working on what they call Tweel, a combined tire and wheel that would not go flat because it contains no air.

Arriving at a conference room recently to explain the development project, a research engineer, Bart Thompson, used the Segway Human Transporter that he rode to the meeting to illustrate his points.

Aboard this self-balancing electric scooter, Thompson whizzed down the hallway and out to the lobby, pirouetting among the benches and planters to demonstrate the flexibility of the Tweel.

The Segway would be a small market for Michelin, the world's leading tire maker, but it is an apt demonstration vehicle for the Tweel. The first commercial use of the integrated tire and wheel assembly will be on the stair-climbing iBOT wheelchair, another product developed by Dean Kamen, the Segway's inventor. Michelin said it would announce another application at the Detroit auto show next week.

The tire maker has high expectations for the Tweel. The concept of a single-piece tire and wheel assembly is one that the company expects to spread to passenger cars and construction equipment and aircraft.

The Tweel offers a number of benefits beyond being impervious to nails in the road. The tread will last two to three times as long as current radial tires, Michelin says, and when it does wear thin, it can be retreaded.

For manufacturers, the Tweel offers an opportunity to reduce the number of parts, eliminating most of the 23 components of a typical new tire as well as the costly air-pressure monitors that will soon be required on new vehicles in the United States.

Manufacturers have devoted an increasing amount of attention to tires that allow motorists to continue driving, at a reduced speed, for at least 100 miles, or 160 kilometers after a puncture. Several such designs are available, providing peace of mind for travelers and cutting the need for spare tires. Michelin sells them under the Pax name.

The Tweel, mounted on a car, is a single unit, though it actually begins as an assembly of four pieces bonded together: the hub, a polyurethane spoke section, a "shear band" surrounding the spokes and the tread band - the rubber layer that wraps around the circumference and touches the pavement.

While the Tweel's hub functions as it would in a normal wheel - a rigid piece that attaches to the axle - the polyurethane spokes are flexible, to help absorb road impacts. The shear band surrounding the spokes effectively takes the place of the air pressure, distributing the load. The tread is similar in appearance to a conventional tire.

One shortcoming of a tire filled with air is that the pressure is distributed equally around the tire, both up and down as well as side to side. That property keeps the tire round, but it also means that raising the pressure to improve cornering - increasing lateral stiffness - also adds up-down stiffness, making the ride harsher.

With the Tweel's injection-molded spokes, those characteristics are no longer linked, holding the potential to improve handling response. The spokes can be engineered to give the Tweel five times as much lateral stiffness as pneumatic tires without losing ride comfort.

The Tweel is in its infancy - "version 1.0," Thompson said, and only one set of car Tweels exists. A test drive in a Tweel-equipped Audi A4 sedan on roads around Michelin's research center proved to be far less exotic than the construction method or appearance would suggest. The prototype Tweels are noisy, as Thompson warned they would be, because the spokes vibrate. (Pictures above.)

Almost everything else about the Tweel is undetermined at this early stage of development, from serious matters like cost to more frivolous questions like the possibilities of chrome-plating.

Other uses - military vehicles, for example - would come before automobiles, but Michelin's business projections accommodate the possibility that the Tweel may not be an overnight success. This would be nothing new for Michelin: The radial tire it invented in 1946 was not widely accepted in the United States until the 1970s